By Guest Author 12/03/2021

Alysha Johnson

Before I headed out to sea, I did not know a lot about the ocean to begin with. A geologist and geomorphologist by training, I have always looked at the land and had never spent longer in a ship than the 3-hour Wellington to Picton ferry crossing. But it hasn’t taken me long to realise that compared to land,  we know so little about our Earth’s oceans. 

Aboard the Schmidt Ocean Institute’s vessel, the R/V Falkor, I have joined the science party for two months of voyaging. We are sailing through the Coral and Tasman Seas bathymetric mapping, seabird surveying, studying ocean currents, seafloor magnetic anomalies and sampling for microplastics.

The regions mapped by the R/V Falkor so far in 2021 in the Tasman and Coral Sea. The blue triangle indicates the R/V Falkor’s position as of 26th of February 2021. Data credit: Schmidt Ocean Institute

Even though both seas are of incredible importance to New Zealand, Australia, and many neighbouring islands, I have been surprised how little we know about it. The well-studied East Australian Current (made famous by some surfing turtles in Finding Nemo) runs along the coast of Australia but is limited to shallow water depths. In this region where the ocean can be as deep as 4500m, we have no idea how water within these depths moves. On top of that, we are not even entirely sure how the Tasman and Coral seas exist. It is known that they formed from the separation of Gondwana, rifting apart from the Australian continent and stopped opening 52 million years ago (Gaina et al., 1998). But sadly, it is not that simple. Multiple microcontinents and smaller-scale tectonic regimes have started noted, and we do not know how the puzzle fits together yet.

Chief Scientist Dr Derya Gürer leads science team through an exercise compiling and exploring seismic data of the Tasman and Coral Sea regions whilst abord the R/V Falkor. Photo Courtesy of Alysha Johnson

Whilst aboard the R/V Falkor, we have started to fill in some of these gaps. We have mapped over 75,000 km2 in the Tasman and Coral Seas, uncovering seamounts, landslides, fault lines, drowned reefs, canyons, dune fields over 10m tall, mountains taller than Mt Wellington in Hobart or volcanoes taller than Mt Taranaki. We have discovered deep-sea currents deflecting and scouring around this dramatic bathymetry and extensive eddies at the surface and continuing to 700m deep beneath the ocean. We have also found seismic anomalies, evidence that could hold clues on how the Tasman and Coral seas opened. We have counted and sampled over seven thousand seabirds in a remote region of the world where the population had previously just been extrapolated. And we have found microfibres and microplastics at surface waters, but also at depths of 4000m.

Top Left: 4000m tall Fraser Guyots in the North Tasman. Image courtesy of Schmitt Ocean Institute
Top Right: Red Footed Boobys battle for spots on the foremast. These are one of the most common birds sighted in the Coral Sea. Image courtesy of Bianca Keys
Bottom Left: Microplastics which were collected from CTD sampling 2155m deep in the Coral Sea. Image courtesy of Lauren Huet
Bottom Right: Previously unmapped Selfridge Ridge and Unnamed Rise. Image courtesy of Schmitt Ocean Institute

The daily excitement of discovery has been incredible, and I have learnt a phenomenal amount whilst becoming immersed in the Taman and Coral Seas. But if we know so little about the oceans on our back doorstep, what do we know about even more remote oceans? It is hard to encapsulate how little we know. Though the ocean covers more than 70% of our Earth’s surface, less than 20% of it has been mapped. Studying our oceans is hard, the logistical issue of penetrating thousands of meters of water still offers extensive challenges to the world’s best engineers and scientists. But just because it is hard does not mean we should shy away.  We know about the surface of Mars than we do about our oceans. And based on how much has been found in one small section of the ocean in two months, I think that the most significant challenge and most critical challenge for our cohesion with this planet is not to study other planets but to understand our own.

Alysha Johnson (@AlyshaJohnsonNZ) is a PhD candidate at the University of Wollongong.